When setting the part cooling fan speed to a percentage it randomly resets itself to 4.7% during the print. This can happen even when the fan slider is off or no number is inserted. It is also difficult to enter a number in the box as random extra decimal places appear off the screen area.

HI

I am using a Prusa I3 Mk2 upgraded clone with Ramps 1.4, A8994 drivers and Mattercontrol.

Recently, after printing perfectly for days, the z axis has started ticking and slowly moving upwards before a print. This only happens between pressing the print button and the hotend moving to its print position.

I have tried:
1. Swapping drivers
2. Setting a lower Vref
3. Checking ease of movement of screw threads

The result is a random Z offset and prints not adhering to the bed.

This does not occur if I export the gcode file to SDram and insert it into the printer. It prints normally

Anyone had the same?

Recently when starting the program I am getting an extra stl file loading at the bottom of the queue. It is always the same file which is one I designed some time ago. If I re-start without deleting it, I get another identical copy below it.

I don't really want to reinstall the program without losing all the setup I have.

Not important, but niggly.

Solved it!

I needed to set :

Print Area, Print Centre - 0,0 It was set - 100 100

General, Centre Print - OFF It was set - ON

Now prints in the centre of the bed.

I have no idea what I have done! I have been printing for months using Mattercontrol with excellent results. Now my Kossel Mini - bed levels, warms up and then shoots off the bed between the Y and Z towers. An emergency reset stops it being silly. A test print with Cura is fine. I haven't the foggiest how to stop it doing this. Any ideas?